Study

Function of the spermaceti organ of the sperm whale

Clarke, Malcolm R.

Nature, 1970

Peer-reviewedphysiological studynot applicable

What they did

Spermaceti wax was sampled and its physical properties — notably the temperature at which it solidifies and the accompanying change in density — measured, then combined with anatomical description of the organ's blood supply and nasal passages to propose a function.

Studied in: Physeter macrocephalus
Sample size: spermaceti samples and anatomical measurement from whaling catches

What they found

Spermaceti solidifies within the range of temperatures the organ can reach, and the associated density change is sufficient to alter the whale's buoyancy meaningfully. The organ has a blood supply and nasal passages capable of cooling or warming it.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The spermaceti organ may serve as a buoyancy regulator, allowing the whale to adjust density for descent and ascent.

How NatureHQ reads it

Included because it is the classic hypothesis, and because the field has largely moved away from it. The buoyancy account is elegant and the physical measurements are sound, but later work found the achievable temperature changes too slow and too small to matter over a dive, and the weight of current evidence treats the organ primarily as acoustic apparatus — a sound generator and lens for the click. Cited here as an example of a well-argued idea that better data did not support, which is a more useful thing for a reader to see than a tidy consensus.

Limitations

Material came from whaling catches, so measurements are post-mortem.
The proposed thermal cycling has not been demonstrated in a living diving whale.
Subsequent work suggests the temperature changes required are not achievable on dive timescales.